Develop Reference

Date Parsing problem while Integrating to Oracle PMS

I'm recieving date in PMS message something like this |GA090616|GD090617|
which means Guest Arrival is at 09-06-16 and Guest Deprature is at 09-06-17
I wanted to parse it as date using python.
I've also visited stack oveflow[1, 2 ...] for this but as solution I've found
from datetime import datetime
self.DATE_FROMAT='%d/%m/%y'
arrival_date=datetime.strptime('90616', self.DATE_FROMAT).date()
print(arrival_date)
and it's not possible to parse it like this due to its unclear format.
I'm not sure if 09 is a month or a date, but from what I've seen in documents and PDFs, it appears to be a month.
Is there any better solution for this kind of date parsing? or suggestions for my expectations.
09-06-16,
09-06-17
Note:
Please Just take the date from the string 090617 and parse it as a date. That will be helpful.

You can do this with regex matching, you can either split the string with msg.split("|") or not, but that depends on your use case.
import re
from datetime import datetime
msg = "GA090616|GD090617|"
DATE_FORMAT='%d%m%y'
ar = re.match("GA(\d{6})", msg)
dp = re.match("GD(\d{6})", msg)
guest_arrival = datetime.strptime(ar.group(1), DATE_FORMAT).date()
guest_departure = datetime.strptime(dp.group(1), DATE_FORMAT).date()
Although not fully tested, this should be a boilerplate as to how to retrieve the date from the message. Remember to remove the \ from the date format, as that is not included in the message.

Best practices to filter in Django

In one of the pages of my Django app I have a page that simply displays all employees information in a table:
Like so:
First Name: Last Name: Age: Hire Date:
Bob Johnson 21 03/19/2011
Fred Jackson 50 12/01/1999
Now, I prompt the user for 2 dates and I want to know if an employee was hired between those 2 dates.
For HTTP GET I just render the page and for HTTP POST I'm sending a URL with the variables in the URL.
my urls.py file has these patterns:
('^employees/employees_by_date/$','project.reports.filter_by_date'),
('^employees/employees_by_date/sort/(?P<begin_date>\d+)/(? P<end_date>\d+)/$', EmployeesByDate.as_view()),
And my filter_by_date function looks like this:
def filter_by_date(request):
if request.method == 'GET':
return render(request,"../templates/reports/employees_by_date.html",{'form':BasicPrompt(),})
else:
form = BasicPrompt(request.POST)
if form.is_valid():
begin_date = form.cleaned_data['begin_date']
end_date = form.cleaned_data['end_date']
return HttpResponseRedirect('../reports/employees_by_date/sort/'+str(begin_date)+'/'+str(end_date)+'/')
The code works fine, the problem is I'm new to web dev and this doesn't feel like I'm accomplishing this in the right way. I want to use best practices so can anyone either confirm I am or guide me in the proper way to filter by dates?
Thanks!

You're right, it's a bit awkward to query your API in that way. If you need to add the employee name and something else to the filter, you will end up with a very long URL and it won't be flexible.
Your filter parameters (start and end date) should be added as a query in the url and not be part of path.
In this case, the url would be employees/employees_by_date/?start_date=xxx&end_date=yyy and the dates can be retrieved in the view using start_date = request.GET['start_date].
If a form is used with method='get', the input in the form are automatically converted to a query and appended at the end of the url.
If no form is used, parameters need to be encoded with a function to be able to pass values with special characters like \/ $%.

Use Unix timestamps instead of mm/dd/yyyy dates. A unix timestamp is the number of seconds that have elapsed from Jan 1 1970. ("The Epoch".) So it's just a simple integer number. As I'm writing this, the Unix time is 1432071354.
They aren't very human-readable, but Unix timestamps are unambiguous, concise, and can be filtered for with the simple regex [\d]+.
You'll see lots of APIs around the web use them, for example Facebook. Scroll down to "time based pagination", those numbers are Unix timestamps.
The problem with mm/dd/yyyy dates is ambiguity. Is it mm/dd/yyyy (US)? or dd/mm/yyyy (elsewhere)? What about mm-dd-yyyy?

Timezone issue with pyExchange

I am working with pyExchange on windows 7 machine. I have a simple python v2.7 script that retrieves the Outlook calendar events from the exchange server. The script is provided below:
Code:
from pyexchange import Exchange2010Service, ExchangeNTLMAuthConnection
from datetime import datetime
import time
from pytz import timezone
def getEvents():
URL = u'https://xxxxx.de/EWS/Exchange.asmx'
USERNAME = u'MS.LOCAL\\xxxxx'
PASSWORD = u"xxxxxx"
connection = ExchangeNTLMAuthConnection(url=URL,
username=USERNAME,
password=PASSWORD)
service = Exchange2010Service(connection)
timestamp = datetime.now()
print timestamp.strftime('%Y, %m, %d, %H, %M, %S')
print time.timezone
eventsList = service.calendar().list_events(
start=timezone("Europe/Amsterdam").localize(datetime(2015, 1, 19, 0, 0, 0)),
end=timezone("Europe/Amsterdam").localize(datetime(2015, 1, 19, 23, 59, 59)),
details=True
)
for event in eventsList.events:
print "{start} {stop} - {subject} - {room}".format(
start=event.start,
stop=event.end,
subject=event.subject,
room=event.location
)
getEvents()
Problem:
The timestamp of the events doesn't match the timestamp of the events in Outlook. I created the events manually using the Outlook as well as using a pyExchange script.
For eg: If I create an event from 11:00 AM - 11:30 AM in Outlook, then the above script will return the timestamp of that event as 10:00 AM - 10:30 AM. The time is one hour less/back.
If I check my time.timezone it returns W. Europe Standard Time. I have specified my timezone in the script too ie. Europe/Amsterdam. But still the problem persists. Also I checked the timezone settings in Outlook. Shown below:
I logged into the Exchange server and it is also in the same timezone as my client machine.
Any suggestion regarding why the time is not correct for the events? Is this a bug in pyExchange? I would really appreciate it, if some one can test this and report back here, just to be sure that its not only me who is facing this issue.

I looked and it's probably not a bug in pyexchange, but how you're handling timezones. No shame, they're sadly extremely confusing in Python.
First, the package is returning event dates in UTC and not your local time. You're seeing an hour off the expected time because your timezone is +1 UTC. Here's an event I pulled from my calendar using your script (this is start/end/name/room):
2015-01-19 20:00:00+00:00 2015-01-19 21:00:00+00:00 - Lunch - Cafe
Note the +00:00 - that means it's in UTC. Noon here in California is 20:00 UTC.
Always, always, use UTC when handling datetimes. Here's some doc from the pytz folk on why localtimes are dangerous.
PyExchange tries to have your back and will convert localtime to UTC, but it always returns UTC. That's on purpose because see the previous link.
Now, to answer your question on getting this to work. First, convert your local time to UTC using these handy tips:
Use datetime.now(pytz.utc) to get the current datetime
Don't use datetime(…, tzinfo=timezone) to create a timezone aware datetime object, it's broken. Instead, create the datetime object and call timezone.localize on it.
For you, that means you have to do ugly stuff like:
start = timezone("Europe/Amsterdam").localize(datetime(2015, 1, 19, 0, 0, 0))
start = start.astimezone(pytz.utc)
Then, when you want to display UTC dates as your own time, do:
event.start.astimezone(timezone("Europe/Amsterdam"))
When I do that, I see this output from your script:
2015-01-19 21:00:00+01:00 2015-01-19 22:00:00+01:00 - Lunch - Cafe
which I would expect. Noon my time is 9pm your time.
Here's a gist of your script that I changed. Take a look and see if it fixes your problem. If not, I'm happy to look again!

Python datetime parsing for SAR logs

I know that there are a lot of datetime parsing questions here and, of course, there are many docs out there on the web but even with all that I'm still scratching my head on the best way to do this after hours of reading, trial and error (and, boy, have there been errors).
So, I need to parse SAR memory logs under linux over a range of days, returning data in JSON format for presentation in graphical format in a browser.
I'm just about there - it looks great in Chrome but I need to improve the output date format to maximise x-browser capability.
So, to do this I need to work with two things
A datetime object that is set to the date of the sar log I'm reading
A string from the log entry in the form '10:01:30 PM'
I want to be able to combine these into a string formatted as 'YYYY-MM-DDT22:01:30'
The bodge I'm using at the moment is
jDict['timestamp'] = d.strftime("%Y-%m-%d") + " " + timeStr
where d is my datetime object and timeStr is the time string from the log entry. Chrome is letting me get into bad habits and is happy to parse that format, but FF is stricter.
EDIT
#dawg below has asked for a sample of input and output
Example sar log format:
05:15:01 PM 2797588 13671876 83.01 228048 8276332 8249908 39.92
05:25:01 PM 2791396 13678068 83.05 228048 8276572 8455572 40.92
05:35:01 PM 2786104 13683360 83.08 228048 8282040 8249852 39.92
Current Output format:
[
{"timestamp": "2014-02-03 01:35:01 PM", "memtot": 16469464, "memused": 15747980},
{"timestamp": "2014-02-03 01:45:01 PM", "memtot": 16469464, "memused": 15791088},
{"timestamp": "2014-02-03 01:55:01 PM", "memtot": 16469464, "memused": 15690408}
]
Obviously I've not matched times and dates here - just some random lines

Or just give up and use moment.js in the browser - that's what I went for in the end. Downside is another library to load but it does just make the problem go away

Making Django queries with localized dates

In my form I have a DateField called booking_date that is rendered with the AdminDateWidget. The contents of the booking_date field needs to be internationalized. The problem appears when I want to use the value of the field in something like this:
booking = Booking.objects.get(booking_number='BN34D', booking_date='2010-11-21')
But if my date format is '%d.%m.%Y':
booking = Booking.objects.get(booking_number='BN34D', booking_date='21.11.2010')
I get a 'ValidationError: Enter a valid date in YYYY-MM-DD format'
How can I make the query regardless of the date format used?

You should parse it first with a localized version of the strftime format.
from datetime import datetime
d = datetime.strptime('...')
booking.objects.get(..., booking_date=d.date())
Use these formats in strptime:
http://linux.die.net/man/3/strftime
You shouldn't rely on passing directly from the user into the query.
Looks like you should be doing the following from your specific example:
d = datetime.strptime('%d.%m.%Y')
booking = Booking.objects.get(booking_nmber='BN34D', booking_date=d)

As I understand your question, you don't know for sure in advance, which locale will be used. That can bring you into unsolvable problems. ("10-11-12" could be Oct 11, 2012 or Nov 12, 2010 or ...)
So you must have a limited, distinguishable set of possible formats. Then you can do:
POSSIBLE_FORMATS = ('%d.%m.%Y', '%Y-%m-%d', '...')
for f in POSSIBLE_FORMATS:
try:
d = datetime.date.strptime(date_str, f)
break
except ValueError:
continue
raise ValueError
booking = Booking.objects.get(booking_number='BN34D', booking_date=d)

I have solved the problem using this:
from django.utils import formats
formats.get_format('DATE_INPUT_FORMATS')[0]
This format is then used for parsing the date like xyld showed.